Power supply apparatus

Abstract

There is provided a power supply apparatus supplying a power to an electronic device, especially, a light emitting diode, capable of stably supplying power to different loads with simple circuit configuration, and maintaining the balance of the current supplied to light emitting diodes.

What is claimed is: 
     
         1 . A power supply apparatus comprising:
 a power supplying unit switching an input power so as to supply at least two powers;   a first control unit controlling primary side switching of the power supplying unit in a predetermined first manner according to the state of one of the at least two powers from the power supplying unit;   a current balancing unit receiving another of the least two powers from the power supplying unit and maintaining the balance of currents between at least two light emitting diodes so as to transfer the power; and   a second control unit controlling secondary side switching of the power supplying unit in a predetermined second manner according to the state of the power transferred to the least one light emitting diode of the at least two light emitting diodes.   
     
     
         2 . The apparatus of  claim 1 , wherein the first control unit controls the primary side switching frequency of the power supplying unit. 
     
     
         3 . The apparatus of  claim 1 , wherein the second control unit controls the secondary side switching duty of the power supplying unit. 
     
     
         4 . The apparatus of  claim 1 , wherein the power supplying unit includes:
 a power switching unit switching the input power under the control of the first control unit;   a transformer having a primary winding receiving the switched powers from the switching units, and a plurality of secondary windings magnetically coupled to the primary winding to have a predetermined turns ratio; and   a switching unit connected to one of the plurality of secondary windings and switching the transferred power under the control of the second control unit so as to transfer the switched power to the current balancing unit.   
     
     
         5 . The apparatus of  claim 4 , wherein the plurality of secondary windings of the transformer is made up of:
 a first secondary winding group having some of the plurality of secondary windings and supplying power to the light emitting diodes; and   a second secondary winding group having the other of the plurality of secondary windings.   
     
     
         6 . The apparatus of  claim 5 , wherein the current balancing unit includes:
 a diode group having a plurality of diodes each connected to both ends of a secondary winding of the first secondary winding group so as to provide a power transfer path; and   capacitors respectively located between one diode of the diode group and a corresponding secondary winding so as to maintain the balance of currents flowing in one direction and the other direction of the corresponding secondary winding.   
     
     
         7 . The apparatus of  claim 6 , wherein each of the at least two light emitting diodes is connected to one end of each of the first secondary winding group via at least one diode of the diode group, or to the other terminal of each of the capacitors with one terminal connected to the other end of each of the secondary windings. 
     
     
         8 . The apparatus of  claim 4 , wherein the first control unit includes:
 a power control unit controlling the switching of the power supplying unit according to the output state of at least one of the powers from the power supplying unit;   a frequency control unit controlling the switching frequency of the power supplying unit according to the switching control of the power control unit; and   a gate driver driving the switching of the power switching unit according to the switching frequency of the frequency control unit.   
     
     
         9 . The apparatus of  claim 8 , wherein the first control unit further includes a transfer unit which has one side to receive a signal and the other side to transmit a signal, electrically isolated from each other, so that the control signal from the power control unit input to the one side is transmitted to the frequency control unit connected to the other side. 
     
     
         10 . The apparatus of  claim 4 , wherein the second control unit includes:
 a PI control unit comparing a current value flowing in one of the at least two light emitting diodes with a command current value; and   a switching control unit comparing the comparison result from the PI control unit with a predetermined reference signal so as to control the switching duty of the switching unit.   
     
     
         11 . A power supply apparatus comprising:
 a power supplying unit switching an input power to supply a predetermined power; and   a current balancing unit alternately supplying the power from the power supplying unit to at least two light emitting diodes according to the switching of the power supplying unit so as to maintain the balance of currents between the at least two light emitting diodes.   
     
     
         12 . The apparatus of  claim 11 , wherein the power supplying unit includes:
 a power switching unit switching the input power according to control;   a transformer having a primary winding receiving the switched powers from the switching units, and a plurality of secondary windings magnetically coupled to the primary winding to have a predetermined turns ratio; and   a switching unit connected to one of the plurality of secondary windings and switching the transferred power according to control so as to transfer the switched power to the current balancing unit.   
     
     
         13 . The apparatus of  claim 12 , wherein the plurality of secondary windings of the transformer is made up of:
 a first secondary winding group having some of the plurality of secondary windings and supplying power to the at least two light emitting diodes; and   a second secondary winding group having the other of the plurality of secondary windings.   
     
     
         14 . The apparatus of  claim 13 , wherein the current balancing unit includes:
 a diode group having a plurality of diodes each connected between both ends of a secondary winding of the first secondary winding group so as to provide a power transfer path; and   capacitors respectively located between one diode of the diode group and a corresponding secondary winding so as to maintain the balance of currents flowing in one direction and the other direction of the corresponding secondary winding.   
     
     
         15 . The apparatus of  claim 14 , wherein each of the at least two light emitting diodes is connected to one end of each of the first secondary winding group via at least one diode of the diode group, or to the other terminal of each of the capacitors with one terminal connected to the other end of each of the secondary windings, so as to receive the power. 
     
     
         16 . The apparatus of  claim 15 , wherein the first secondary winding group includes N secondary windings, wherein N is a natural number equal to or greater than 1, and the other end of each of the N secondary windings is connected to one end of and adjacent secondary winding via at least one diode of the diode group so as to supply power to (N+1) light emitting diodes. 
     
     
         17 . The apparatus of  claim 13 , further comprising:
 a first control unit controlling primary side switching of the power supplying unit in a predetermined first manner according to the state of one of the at least two powers from the power supplying unit; and   a second control unit controlling secondary side switching of the power supplying unit in a predetermined second manner different from the first manner according to the state of the power transferred to at least one light emitting diode of the at least two light emitting diodes.   
     
     
         18 . The apparatus of  claim 17 , wherein the second control unit controls the secondary side switching duty of the power supplying unit. 
     
     
         19 . The apparatus of  claim 17 , wherein the first control unit includes:
 a power control unit controlling the switching of the power supplying unit according to the output state of at least one of the powers from the power supplying unit;   a frequency control unit controlling the switching frequency of the power supplying unit according to the switching control of the power control unit; and   a gate driver driving the switching of the power switching unit according to the switching frequency of the frequency control unit.   
     
     
         20 . The apparatus of  claim 17 , wherein the second control unit includes:
 a PI control unit comparing a current value flowing in one of the at least two light emitting diodes with a command current value; and   a switching control unit comparing the comparison result from the PI control unit with a predetermined reference signal so as to control the switching duty of the switching unit.